Search results for "Coaxial"
showing 10 items of 62 documents
Flexible and efficient computer-aided design tool for advanced comb-line rectangular waveguide filters
2015
A very flexible and efficient computer-aided design CAD tool, specifically suited for advanced comb-line rectangular waveguide filters, is presented in this work. The developed software tool, which makes use of a full-wave analysis technique based on the Boundary Integral-Resonant Mode Expansion method, allows loading the considered comb-line resonators with any number of radially symmetrical partial-height metallic posts. The implemented CAD tool also allows dealing with coupling windows of arbitrary cross-section, thus drastically enhancing the flexibility of the CAD process. The excitation of the analyzed components, which is performed using generalized coaxial probes, has also been inte…
Novel multipactor studies in RF satellite payloads: Single-carrier digital modulated signals and ferrite materials
2017
In this work it is reviewed the most novel advances in the multipactor RF breakdown risk assessment devoted to RF satellite microwave passive devices employed in space telecommunication systems. On one side, it is studied the effect of transmitting a single-carrier digital modulated signal in the multipactor RF voltage threshold in a coaxial line. On the other hand, an analysis of the multipactor phenomenon in a parallel-plate waveguide containing a magnetized ferrite slab it is presented.
Analytical induced force solution in conducting cylindrical bodies and rings due to a rotating finite permanent magnet
2020
Abstract Using exact expression of the magnetic field we derive analytical expression for the induced current density and volume force in a solid conducting cylinder and ring due to a coaxial rotating finite permanent magnet with transverse magnetization. The integral torque is calculated from these expressions and validated with numerical and experimental results. Conditions for useful magnetic field approximations are found.
Biaxial Microincision versus Coaxial Small-Incision Clear Cornea Cataract Surgery
2005
Objective To compare clinical outcomes of biaxial microincision (1.5 mm) and coaxial small-incision (2.75 mm) clear cornea cataract surgery. Design Randomized controlled clinical trial. Participants Seventy eyes of 70 patients were examined at a German university eye hospital. Intervention The 70 patients (70 eyes) were assigned randomly (1:1) to a biaxial or conventional coaxial incision group. Both groups underwent phacoemulsification using pulsed ultrasound energy with variable duty cycles, followed by microincision intraocular lens implantation. Main Outcome Measures Best-corrected visual acuity (BCVA), astigmatism, laser flare photometry value, effective phacoemulsification time (EPT),…
Optical coherence tomography of macular thickness after biaxial vs coaxial microincision clear corneal cataract surgery
2009
PURPOSE To evaluate macular thickness changes after biaxial microincision versus coaxial small incision cataract surgery using optical coherence tomography (OCT). METHODS This prospective, randomized, marked study comprised 70 patients (70 eyes) undergoing biaxial microincision surgery or conventional coaxial phacoemulsification. Patients were evaluated by Stratus OCT preoperatively and 1 day, 4 weeks, and 8 weeks postoperatively. Best-corrected visual acuity (BCVA), phacoemulsification power, and effective phacoemulsification time (EPT) were evaluated. RESULTS In the biaxial group, median foveal thickness changed from 160 microm preoperatively to 168 microm 8 weeks postoperatively (p=0.018…
A circular mesh scheme for the non-orthogonal finite difference time domain method
2002
Beam forming networks (BFN) are an important component of a complex satellite antenna system because they are used to provide accurate amplitude and phase excitation to the elements of the feed network. The need for handling high power and the need for a high degree of integrability, often leads one to choose square coaxial metal lines for constructing BFNs. BFNs usually require variable power dividers such as the rat-race (or ring) couplers with constant or variable divider ratios in order to deliver a prescribed amount of power to a certain element of an antenna array to steer the beam in a desired direction. However, modeling of such circular structures in square coaxial form is not an e…
Development of a dielectric spectroscopy technique for the determination of apple (Granny Smith) maturity
2010
Abstract Dielectric measurements of apple were done during its maturity in order to find relations with apple physiological compounds (sugar content, malic acid). An Agilent 85070E open-ended coaxial probe connected to an Agilent E8362B vector network analyzer were used in these experiments. All determinations were made at 30 °C from 500 MHz to 20 GHz. These assays were performed in order to consider the potential use of dielectric spectroscopy for determining the state of fruit maturity. Good correlations among apples Thiault Index with a new defined Dielectric Maturity Index were found. The Dielectric Maturity Index was related to loss factor at two punctual frequencies (0.5 GHz and dipol…
Linear Waves in Electrical Transmission Lines
1996
Nowadays, linear transmission lines provide vital links in virtually all communications and computer systems, and the parallel-wire line is still widely used today in open-wire form, in coaxial cables and microstrips. The standard twoconductor transmission line is an important familiar system, that is able to support the propagation of transverse electromagnetic modes and is of great interest in many practical situations. We have all often studied this electrical circuit or variation of it in elementary electronics, physics, or mathematics courses (Ramo et al. 1965, Davidson 1978, Badlock and Bridgeman 1981). In fact, the study of linear transmission lines is an old problem: in their simple…
Highly efficient full-wave electromagnetic analysis of 3-D arbitrarily shaped waveguide microwave devices using an integral equation technique
2015
A novel technique for the full-wave analysis of 3-D complex waveguide devices is presented. This new formulation, based on the Boundary Integral-Resonant Mode Expansion (BI-RME) method, allows the rigorous full-wave electromagnetic characterization of 3-D arbitrarily shaped metallic structures making use of extremely low CPU resources (both time and memory). The unknown electric current density on the surface of the metallic elements is represented by means of Rao-Wilton-Glisson basis functions, and an algebraic procedure based on a singular value decomposition is applied to transform such functions into the classical solenoidal and nonsolenoidal basis functions needed by the original BI-RM…
A new bi-faced log periodic printed antenna
2005
In this paper, a new design of a broadband planar printed antenna based on the academic log periodic antenna is presented. The antenna consists of a series of printed dipoles, distributed on both faces of the substrate. Some configurations are explored, with a different number of printed dipoles. These are designed, simulated, fabricated, and measured. The calculated and measured return losses and radiation patterns are presented. The utility of the proposed antenna associated with its frequency bandwidth is better than 80%. The measured absolute gain is 6.5 dBi, and the front-to-back ratio is around 8 dB. The presented antenna should find wide applications in wireless communication systems…